The present invention relates generally to the field of downhole water separation, and more particularly, but not by way of limitation, to a downhole water separation system having a submersible pump.
Fluid separation systems are an important and expensive part of most hydrocarbon production facilities. The separation of fluids based on different properties is known in the industry. A variety of separation methods are used, including gravity separators, membrane separators and cyclone separators. Each of these separator types uses a different technique to separate the fluids and each achieves a different efficiency depending upon the device and its application.
Gravity separators, for instance, can be efficient when there is a great density difference between the two fluids and there are no space or time limitations. Another type of separator, the membrane separator, uses the relative diffusibility of fluids for separation. Any separation method that is time dependant, such as the above mentioned gravity and membrane separators, does not work well with an electric submersible pump due to the high pressure and rates involved with these pumps.
Electric submersible pumps (ESP) are capable of producing fluids in a wide volume and pressure range, and thus submersible pumps are often used for downhole fluid production. Such pumps are also used very efficiently for applications where downhole oil water separation devices are used. As already noted, gravity and membrane separators do not work well with an electric submersible pump. Hydro cyclone separators, on the other hand, have been used effectively with electric submersible pumps, both on the surface and in below the surface applications.
Hydro cyclone separators are non-rotating devices, using a specific geometric shape to induce fluid rotation. The fluid rotation creates high g-forces in the fluids as the fluids spin though the device, resulting in the lighter fluids forming a core in the middle of the separator. In the separation of oil and water mixtures, the inner core is extracted out of the topside of the hydro cyclone separator as an oil stream. The separated water is rejected from the bottom side. One problem associated with this type of separator is the large pressure drop experienced as the fluid passes through the hydro cyclone.
A system design that incorporates use of an ESP system with a hydro cyclone is often complicated. Depending upon the relative locations of the disposal and production zones, these systems usually have one or two conduits running from the separator and pump to the respective zones or are limited on where the systems can be placed in relation to the positioning of the pumps. The conduits not only cause excessive pressure drops in the fluids but also arc the weak links in the design, often causing mechanical problems during installation.
There is a need in the industry for a more efficient, simpler device for separation of different density fluids that is capable of operating in smaller diameter wellbores.
The present invention provides a system using a separation device in conjunction with an encapsulated submersible pumping device.
The present invention provides a downhole water separation system coupled with an encapsulated electric submersible pumping device for the separation and transfer of fluids of different densities in downhole applications. The encapsulated device works in conjunction with a separator and packer, having a pump assembly and a motor assembly that are contained in an enclosed device to separate fluids with a minimum use of conduits. Since the pump and motor are part of an encapsulated single device, the separation system arrangement is not restricted to one in which the motor and pump must be directly above or below the separator.
The objects, advantages and features of the present invention will become clear from the following detailed description and drawings when read in conjunction with the claims.